For a normal-temperature cable, a three-core collective-type cable is available. In forming a joint of such a three-phase collective-type cable, twisted phases thereof are loosened into each core to be held at an appropriate spacing with each other and then each separated core is lead to the junction. In this stage, since the normal-temperature cable has a relatively small constraint on bending, such a separation structure can be obtained simply by bending each cable core without using any jig.
Furthermore, for a superconducting cable using a high-temperature superconducting tape wire made of a Bi systems, a three-core collective-type cable has also been developed. In that case, a structure where each core thereof is initially spaced apart and then lead to the joint is required.
However, the high-temperature superconducting cable suffers from much severer bending constraint than the normal-temperature cable because when the high-temperature superconducting wire made of a Bi systems is bent, critical current is lowered. In addition, a large amount of thermal shrinkage of the cable occurring during cooling must be accommodated. Accordingly, if each core thereof is simply bent without using any jig as in the case of the normal-temperature cable, abnormal deformation exceeding the tolerable level can occur during the shrinkage. Therefore, there is a need for a solution to this problem.
Accordingly, a main object of the present invention is to provide a phase separation jig for a superconducting cable which can avoid excessive bending stress imposed on a phase separation section, and an separation structure using the jig.